The rain stain effect

Researchers show that acid rain is fuelling the ever-increasing rate of aging, drought, concomitant pollution disorders and tree mortality

It is a popular term — too up-to-the-minute and perforce, in more ways than one. It simply stands for precipitation of pollutants resulting from a host of human activities, natural events and excess load of sulphates and nitrates, including heavy metals and toxic organics. You guessed it right — acid rain.

Acid rain, a simple parenthesis albeit the idiom, encompasses a perplexing facet for the concentration of dissociated hydrogen ions — or excess pH. Let us place the context in perspective. Pure water, for example, has a theoretical pH — or hydrogen ion activity of a system of 7.0, which is equivalent to neutral pH. In actual terms, the full pH range is 0 to 14 — the very acid to the very basic, respectively. Let us illustrate a paradigm — when there is a 10-fold increase in hydrogen ions, for instance, it reduces the pH by one unit.

The measurement of pH is uncomplicated. In reality, however, it isn’t. For the simple reason that obtaining precision and accuracy for evaluating the pH of precipitation and surface water is awfully uncertain — even with the best of equipment and immaculate standards of application and care. Besides, the problem of measuring pH is related to the total ionic strength of the solution of the given sample. As a matter of fact, it is much more undemanding to accurately measure the pH of the nectar of life — water — with its many dissolved minerals than the pH of extremely diluted water with precipitation. This is precisely the reason why scientists use the advanced pH metre, not the routine pH paper available from scientific suppliers — to rule out the possibility of trial and error.

The earliest caveat for the acid rain phenomenon reported was loss of fish colonies in Scandinavia, and later across the US. Of course, it was not easy to establish that acid rain was the actual cause of fish deaths for a host of reasons — inadequate data, lack of environmental studies or sampling frequency, and untenable methodology. All the same, a group of scientists, undeterred by criticism, concluded that acid pollution was, indeed, the causal factor behind certain environmental shadiness, including fish deaths — irrespective of sceptics’ sweepstakes. This was confounded by the problematic separation of acid deposition effects. Picture this: It’s only when the pH drops below 3.0 does clear damage occur — the reason being that the soil provides a natural buffer against the impact of acidity above pH 3.0. This is nothing short of a thin, but big dividing line.

When coal and oil, otherwise known as fossil fuels, are burned, they spawn gaseous discharge — sulphur dioxide and its nitrogenous products. Once these pollutants are released into the atmosphere, they are transfused into acids within weather systems crossing a particular area or country. It is agreed that appropriate conditions of temperature, moisture, chemical catalysts and light are some of the prerequisites for the transformation of this polluted decoction into acids. The old adage, ‘what goes up must come down,’ therefore, holds good — even though some portion of the pollutants may seek the refuge of the clouds and form a nuclei of latent raindrops. When they are conveyed across far distances, along a storm’s path, they meet their nirvana — they fall as fog, sleet, snow and/or rain.

However, not everything gets dissipated through this wet deposition, because some pollutants do not combine with cloud moisture. They fall as dry particles on the landscape. In like manner, certain gases that are not attracted by wet patterns come in contact with the earth’s surface, far removed from the atmosphere. They are converted into acids by precipitation and/or dew formation later.

This is not all. The backdrop for the whole exercise, or the origin of pollutants, comes from industrial combustion and vehicular traffic — automobiles, airplanes and so on. When pollutants emitted by industries, fireplaces, motor vehicles, forest fires and volcanoes rise into the atmosphere, usually under the warm influence of the sun, they merge with oxygen in the air and water vapour to form various acidic compounds — both wet and dry. All the same, or whatever the form of acid pollution, the amount of deposition slides down as the distance from the source expands. This elevates biological risks. It may also transform the course of human life.

Acid rain is not a contemporary spectacle. In plain terms, it all began with the industrial revolution — and, became a bogey in the emerging high-tech world of the early 1980s. More recently, researchers have shown that acid rain, along with several alternate causes, forms a sepulchral monument to the ever-increasing rate of tree-mortality, to cite but just one example. As for others — aging, drought, disease, damage and concomitant pollution disorders — they are collectively referred to as ‘multiple tree syndrome.’

The parallel effects of acid rain are, perhaps, not obvious. They have also been ignored. For instance, metal, cement, stone and paint are all damaged to an extent by acid pollutants. Automotive paints are specifically vulnerable. Think of the sonorous simile — when it rains, it stains.

It goes without saying that the term acid rain evokes a sense of appalling environmental degradation. Yet, it is strange that the world, barring a warped voice here and there, has remained too complacent, despite the steady progress of research, which has gradually drawn a line between guesswork and extremes. Researchers now think of acid rain not as an impending or inescapable doom, but as a significant opportunity with resourceful solutions. For one simple reason — the entity has a definitive bearing on life on earth, most notably, water resources, forests and visibility in the atmosphere, including human health and wellness.

Acid rain may not directly affect human health because the acid in rainwater is too dilute to have direct unpleasant effects. However, medical researchers agree that air pollution — sulphur dioxide and nitrogen oxide — can trigger respiratory disorders, such as bronchitis and asthma, or can make them worse in susceptible individuals. This happens because the pollution that causes acid rain creates tiny, offending particles. When they gain entry into our lungs, they activate such latent health problems, or make existing health problems worse.

Nitrogen oxide in the ground-level ozone is a trigger, no less, for pneumonia, not to speak of lung damage, in the long-term. While it may be reiterated that certain health effects that people have to be concerned about are not actually caused by acid rain, what plays the spoilsport is when people breathe in tiny particles, or ozone. Swimming, for example, in an acidic lake or walking in an acidic cesspool may be no more detrimental to people than swimming or walking in clean water. Yet, the point is ozone affects human health with certain morbidity and mortality risks — for example, asthma and emphysema, a progressive disorder of the lungs.

In like manner, breathing problems and lung disorders in children have been linked to acid air pollution. The argument is everything we eat, drink and breathe has at some point come in contact with acid deposits. Statistics suggests that acid rain-related health issues account for 500 premature deaths, 1,500 emergency room visits and, 200,000 asthma symptom days, each year, in the US and Canada.

The paradox is palpable. The buzzword in the acid rain debate remains as strong as ever — of archetypal ambiguity, in spite of new scientific advance and analyses. It remains to be seen how long the phenomenon will continue to be the ‘acid test’ in man’s ingenious quest to finding the right solutions to problems — complex and complicated. zz